Spatial distribution of nitrogen in the soil , biomass and nitrogen contents of Typku laufolia community, Polygonum hy-dropiper community, Juncui effuses community and Phragmites commanis community in the Zhucao river mouth wetland into Daxi Reservoir in Liyang City , Jiangsu Province were studied. Significant differences of aboveground biomass, belowground biomass and nitrogen contents of four plants were found. Soil loss on ignition ( LOI) , total nitrogen (TN) and nitrate nitrogen ( NO3- -N) concentrations showed decreasing trend on the vertical distribution with increasing depth. Ammonium nitrogen ( NH4+ -N) concentrations in soil profiles decreased first, and then increased. Soil nitrogen concentrations of the four plant communities were different, but most of them were higher than the control, and organic nitrogen was the main form, indicating that the wetland had a certain nitrogen storage capacity and different plant communities affected the distribution of nitrogen. The correlations between LOI and total nitrogen, ammonium nitrogen, nitrate nitrogen were significant. Inorganic nitrogen constituted only a small proportion (1.41% ) , which indicated that the nitrogen mainly presented in the organic form. However, there was nearly no correlation between biomass, nitrogen contents of four types of plant and nitrogen concentrations of each soil layer. This indicated that soil nitrogen contents were affected not only by the form of plant growth, but also by the plant root zone environment, the number and activity of microorganisms.%对江苏省溧阳市大溪水库的洙漕河河口湿地中香蒲、水蓼、灯心草和芦苇四种植物生物量、氮含量及植物群落的土壤氮素分布特征进行研究,结果表明:四种植物地上生物量、地上组织氮含量、地下生物量、地下组织氮含量存在显著差异；土壤烧失量(LOI)、总氮(TN)、硝态氮(NO3--N)在垂直分布上表现为由表层向下减少的总体分布趋势,铵态氮(NH4+-N)浓度的剖面变化呈现先减少后增加的趋势；四种植物群落土壤氮浓度各不同,但均大于对照,以有机氮为主,说明湿地具有一定的储氮能力；不同的植物群落影响湿地氮素的分布相关性分析显示,土壤LOI与TN、NO3--N和NH4+-N均存在极显著相关性,无机氮构成比例较小,仅为1.41％,表明土壤中的氮素主要以有机氮的形式存在；土壤氮浓度与植物生物量及组织氮含量相关性不大,说明土壤氮形态浓度不仅受到植物生长的影响,同时也可能受到植物根区环境、微生物数量与活性等的影响.
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